Update: Success on hives following PI

OK -- big disclaimer, first, that I AM NOT A MEDICAL PERSON, AND that this just one person's experience with an over-the-counter remedy. I had the hives following a regular poison ivy exposure recently that others have described, just as I've had it in past summers. Previously, the hives lasted all summer, and would flare up when contacted by clothing, etc. -- it was agonizing when I was trying to jog, because that would bother it. And it was discouraging that the hives would recur for weeks on end in the same locations.

So, in the last couple weeks, since the hives showed up, I decided to attack them. I've been using Cortaid, which is a 1% cortisone cream, available over the counter. I've used it on the hives, and the ones on which I've used it most regularly (a couple are towards the back of my legs, so I forget about them if they're not making me crazy) have essentially gone away. I have had a couple new hive locations start up, but they, too, appear to be responding to the Cortaid.

I would recommend that you talk to your doctor or the pharmacist about this ESPECIALLY if you're currently taking prednisone or other steroid treatment -- with some drugs, they really discourage simultaneous oral and topical use. But if you're not taking anything and aren't sensitive to topical meds, it might be worth an experiment.